Making Agar Slants (Slopes) - In Pictures
- gregorach
- Under the Table
- Posts: 1912
- Joined: Wed Jun 08, 2011 10:07 am
- Location: Edinburgh
- Contact:
Re: Making Agar Slants (Slopes) - In Pictures
If they were unopened since autoclaving, then you didn't cook them for long enough. Those vials should be completely airtight if they're tightened properly.
Cheers
Dunc
Dunc
Re: Making Agar Slants (Slopes) - In Pictures
I've noticed these ones don't tolerate much internal pressure when you fill with wort and shake up your slant. Tend to fizz out. So probably not absolutely airtight
- gregorach
- Under the Table
- Posts: 1912
- Joined: Wed Jun 08, 2011 10:07 am
- Location: Edinburgh
- Contact:
Re: Making Agar Slants (Slopes) - In Pictures
Well, you ideally should be using containers that are absolutely airtight. Your agar will dry out otherwise.
I still don't think there's much chance of mould spores getting in though - if they could, Pasteur's swan-necked flask experiment wouldn't have worked.
I still don't think there's much chance of mould spores getting in though - if they could, Pasteur's swan-necked flask experiment wouldn't have worked.
Cheers
Dunc
Dunc
Re: Making Agar Slants (Slopes) - In Pictures
These were cooked at max for 25 mins from solid steam hiss. However I also sterilise my rinse jars in the same cook which are 2/3rds full of water. So perhaps should aim for 40 mins...
Re: Making Agar Slants (Slopes) - In Pictures
What is this all about? What is slanting? Why do it?
- Befuddler
- Even further under the Table
- Posts: 2472
- Joined: Sat Dec 19, 2009 2:06 pm
- Location: Edinburgh
Re: Making Agar Slants (Slopes) - In Pictures
It's a method of isolating and storing healthy yeast.nastyphoenix wrote:What is this all about? What is slanting? Why do it?
"There are no strong beers, only weak men"
Re: Making Agar Slants (Slopes) - In Pictures
This is a really interesting topic. Must be my school science background coming back to me! Found this on YouTube Maybe not exactly the same as Wolfy's method, as the yeast is captured from a bottle. However, he also shows how to make a starter from a slant in another video.
Re: Making Agar Slants (Slopes) - In Pictures
The rest of that batch were all not sterile. It took months at room temp but eventually they all failed. The worrying thing is some of that batch have been inoculated so I should really discard the lot, even though no infection is evident in the refrigerated slants. Must try harder....I best identify the relevant dates. If there is no visual clue to a small rogue colony on the chilled slants would you still discard?gregorach wrote:Well, you ideally should be using containers that are absolutely airtight. Your agar will dry out otherwise.
I still don't think there's much chance of mould spores getting in though - if they could, Pasteur's swan-necked flask experiment wouldn't have worked.
After all if you slant from recovered bottle yeast it is not completely free of foreign microbes anyway, nearly but not 100%.
- gregorach
- Under the Table
- Posts: 1912
- Joined: Wed Jun 08, 2011 10:07 am
- Location: Edinburgh
- Contact:
Re: Making Agar Slants (Slopes) - In Pictures
I'd probably streak some plates to isolate clean yeast from the suspect slants.
Cheers
Dunc
Dunc
Re: Making Agar Slants (Slopes) - In Pictures
Good idea...but its a lot of work aint it?
- gregorach
- Under the Table
- Posts: 1912
- Joined: Wed Jun 08, 2011 10:07 am
- Location: Edinburgh
- Contact:
Re: Making Agar Slants (Slopes) - In Pictures
Yeah, it's a right pain in the arse sometimes...
Cheers
Dunc
Dunc
Re: Making Agar Slants (Slopes) - In Pictures
Am having a go again at getting some isolated yeast colonies from a slant. So 2- 3 days at 20C is best for the colonies from single cells to be evident ? Noticed at 1.5% agar the plates were pretty liable to be torn with the loop unless you were very light handed...I'll pop a photo up .... if its worth posting!gregorach wrote:Right, first off, if nobody's said this yet: you clearly need the yeast book.
This is (more or less) what a streaked plate is supposed to look like:
It's not perfect, because the colonies from the last set of streaks aren't as well isolated as I would like, but it's not bad. i'm not getting any of the really good ones out long enough to photograph...
I've never had very good results with the streaking patterns usually recommended - rather than using a zig-zag pattern, I streak a number of not-quite-parallel lines at each step. Hopefully you can see the pattern in the photo. One thing to remember is that you need to flame the loop between each "set" of streaks.
1: Take a tiny sample from your yeast source, pick up the plate, and run the loop back and forward several times in a short line near the edge of the plate - you need to be able to track where this is, so I do it next to my left thumb when holding the plate. Put the plate back down and rinse your loop. (I like to rinse at this stage so that you don't end up with crud burnt onto the loop.) Rotate the plate clockwise through about 45 degrees.
2. Flame the loop. Pick up the plate (keeping it inverted for now), cool the loop by touching it to an area of the plate you're not going to be working near (if you've picked the plate up in your left hand, this is likely to be somewhere around the edge of your palm on the far side from your thumb. You can see the distorted area where I cooled my loop on this plate near the bottom of the photo.) Turn the plate over and quickly draw a set of streaks across the line you did in step 1. Put the plate back down and rotate it clockwise again.
3. Using the same technique, do another two sets of streaks, flaming the loop each time.
Incubate for two or three days, and you should have a lovely plate like mine.
- gregorach
- Under the Table
- Posts: 1912
- Joined: Wed Jun 08, 2011 10:07 am
- Location: Edinburgh
- Contact:
Re: Making Agar Slants (Slopes) - In Pictures
Yeah, I think 2 or 3 days usually does the job... You can always leave it longer if need be.
You need to have a pretty light touch with all of this sort of stuff, but you could up the proportion of agar to produce a stiffer medium if need be.
You need to have a pretty light touch with all of this sort of stuff, but you could up the proportion of agar to produce a stiffer medium if need be.
Cheers
Dunc
Dunc
Re: Making Agar Slants (Slopes) - In Pictures
Regarding storage they say leave them upside down. However that means that mould spores can fall down the crack between the lid and bottom (now top). I have left them upside down but in a plastic bag and with florists parafilm round. Being paranoid again!
- gregorach
- Under the Table
- Posts: 1912
- Joined: Wed Jun 08, 2011 10:07 am
- Location: Edinburgh
- Contact:
Re: Making Agar Slants (Slopes) - In Pictures
Yeah, I always keep them wrapped. I just use cling film.
Cheers
Dunc
Dunc